Historically, our ancestors formed yarns manually from masses of wool or cotton. The principle of a highly developed spinning process originating from this manual spinning process through a great number of various advances and improvements is attributed to this simple manual operation.
When our ancestor prepared a yarn with his own hands, as shown in FIG. 1, he picked up the yarn end by fingers of the right hand and turned the yarn between the thumb and forefinger to impart twists to the yarn, while he had a cotton mass on the left hand and picked it up to supply fibers. It is construed that this simple operation includes the following four spinning methods.
The first method is one in which the formed yarn is being entirely rotated and it is pulled to the right (in the X direction) without disconnecting the yarn from cotton, to impart true twists to the yarn. This method is known as the ring spinning. It is known that in this method, the amount of the yarn wound is limited and since the yarn is rotated, also the spinning speed is limited (the spinning speed being 13 m/min in case of cotton count Ne 45). As will readily be understood from the fact that cotton counts Ne of yarns heretofore used through our long history have been in the range of 10 to 100, this spinning method has provided us with high quality yarns for our clothing articles.
The second method is one in which a cotton mass is rotated contrary to the first method in which the yarn is rotated. This method can be worked theoretically, but this method has not been practically worked.
The third method is a modification of the second method in which very small amounts of fibers are separated from a cotton mass in succession and thus supplied, and the so supplied fibers are caught on the end of the spun yarn and the yarn end is freely rotated, to form an actually twisted spun yarn. This method is known as the open-end spinning method. Some methods embodying this princple, which differ in the manner of separating small amounts of fibers in the free state from the cotton mass, are known in the art. As a typical instance, there can be mentioned a rotor type open-end spinning process disclosed in the specification of U.S. Pat. No. 3,368,340. More than 5000 spinning machines according to this rotor type open-end spinning process have been practically worked in the art, but in view of working results obtained in these 10 years, it has been confirmed that it would be difficult to enhance the spinning speed because of limitations imposed on the energy consumption and yarn quality. Further, from the economical and technical viewpoints, it is said that preferred cotton counts Ne are in the range of 6 to 45, and it is construed that it is very difficult to spin yarns finer than those of cotton count Ne 40. Moreover, because of the tenacity and structure of the spun yarn, the final application range of the yarn spun according to this spinning process is considerably limited. However, as compared with the first-mentioned ring spinning process, is advantageous with respect to the spinning speed (the yarn speed being 40 m/min on the supposition that the cotton count is Ne 45 for comparison with the ring spinning process where the popular cotton count is Ne 45). In another instance of the open-end spinning process disclosed in the specification of U.S. Pat. No. 3,851,455, fibers are gathered in the form resembling a rope thrown by a cowboy, and the principle of this spinning process is not substantially different from the above-mentioned rotor type open-end spinning process in connection with the fiber-gathering manner, but since pneumatic fluids are utilized, the spinning speed can be enhanced (110 m/min on the supposition that the cotton count is Ne 45 for comparison with the ring spinning process where the popular cotton count is Ne 45). It is said that applicable cotton counts are in the range of from Ne 10 to Ne 30.
The fourth method is one in which either the cotton mass or the resulting yarn is rotated, the connection of fibers to the resulting yarn is not broken, and false twists are given to the resulting yarn to move the fibers and recover the spun yarn. This method is known as the false-twisting process. Typical instances of this spinning process are disclosed in the specifications of U.S. Pat. Nos. 3,079,746 and 3,978,648. According to these known processes, free fibers are actually twisted and wrapped on a non-twisted core yarn. Accordingly, it is indispensible that the cotton mass is sufficiently expanded to form free fibers, and expanded ribbon bundles are supplied in parallel to one another and are taken up by a suction device and twisted by a false-twisting device. The spinning process of this type is in agreement with the ring spinning process in the point that the connection state is substantially maintained between the mass of fibers and yarn, but it is different from the ring spinning process in the point that the formed yarn is not entirely rotated. From the above-mentioned specifications it is seen that in this false-twisting process, the spinning speed is very high, but the process inevitably involves a defect that since fibers are merely wrapped and wound on the core yarn, the yarn strength is insufficient. In the self-twisting process disclosed in the specification of U.S. Pat. No. 3,443,370, a yarn is formed by mechanical false-twisting. It is said that applicable counts are in the range of Ne 12 to Ne 40 and the spinning speed is high (200 m/min on the supposition that the count is Ne 45 for comparison with the ring spinning process where the popular count is Ne 45).